CHEMORADIOTHERAPY (COURSES 3-4): Beginning 2 weeks after completion of induction chemotherapy, patients receive cisplatin and irinotecan hydrochloride as in induction chemotherapy on days 1 and 8 of courses 3 and 4 and undergo radiotherapy daily 5 days a week in course 3. Treatment repeats every 21 days for 2 courses in the absence of disease progression or unacceptable toxicity.